1. Field of the Invention
The present invention relates to a high frequency transformer which is widely and extensively utilizable as a high frequency transformer used in a high frequency range such a TV broadcasting frequency range and a power transformer for switching power source, and more particularly to a plane transformer (sheet-type transformer).
2. Description of the Related Prior Art
In the high frequency transformers of the type described above, in order to avoid a skin effect and a proximity effect, large-diameter wire cannot be adopted. Accordingly, an attempt has been made to provide and use of the parallel winding of a thin and fine wire. Additionally, in recent years, use of the sheet-like coil has been a general trend with a progress and development of the conductive pattern production technique.
However, in a conventional structure, as shown in FIG. 6, the same arrangements are adopted on surfaces A and B and, because of an influence of leaking magnetic flux in magnetic field near a gap (g) at the center leg of EI core, a difference in induced voltage is generated between the coils "a" and "b", so that a loss due to ring current (eddy current), which has not previously been regarded as so important, is increased.
That is, in a coil region of a transformer, the magnetic flux physically linking differs between the aforementioned coils "a" and "b", so that eddy current circulated to the coils "a" and "b" is generated.